Comparative assessment of metal leaching from construction and demolition waste with and without architectural paint

The reintegration of construction and demolition waste (CDW) into the production chain is essential for promoting circularity in the construction sector. However, the use of recycled aggregates and other CDW-derived materials must be conditioned to an assessment of their environmental safety. Architectural paints present on building surfaces often contain heavy metals and other toxic compounds. This study evaluated the influence of paints in CDW on both leaching and solubilization of metals, focusing on potential environmental risks. Paint chips (detached paint fragments) and CDW samples were chemically characterized and extracts obtained from NBR 10.005 leaching test, Synthetic Precipitation Leaching Procedure (SPLP), and NBR 10.006 solubilization test were analyzed for metal concentrations. Lead in paint chips ranged from below the detection limit to 1183.96 mg/kg, whereas chromium ranged from below the detection limit to 104 mg/kg. Despite those variations, Spearman correlation tests showed no significant relationship between paint composition and metal concentrations in leachates or solubilized extracts (p > 0.05) and the presence of paint did not influence the analyzed parameters significantly. Both painted and unpainted samples showed potential for groundwater contamination, with no statistically significant differences under the condition tested, between groups according to Mann–Whitney test at the 5% significance level.